What I am looking to get you to do for Code 34, is "T" into the ERG Valve vacuum connection. Watch and record the different vacuum during the KOER Self-Test. You will need a vacuum gage, a vacuum “T”, and short piece of vacuum hose.

The test increases the idle a few times, during these increases the ECA will signal your EGR Solenoid to open its valve and allow the vacuum to be applied to the EGR.

There are always multiple possibilities for a single code, I think I would start there.

 

I must have mis-interpreted. These diodes are in parallel and not in series?

 

Yes, parallel.

 

Yes, I would say parallel.

 

OK. Let's see if I have this right. The "T" connects to the vacuum hose that runs from the top-side of the EGR valve. The other side of the "T" connects to the TGR valve. The other part of the "T" connects to the vacuum gauge. Right? During the KOER test, am I to follow the instructions and turn the steering wheel/pump the brakes? If so, will the vacuum gauge keep the readings registered? Or do I just let the test increase the idle and watch the gauge so I can see what is going on?

 

Pretty sure you don't need to turn the steering wheel or pump brakes on your truck. There's no sensors there. You may get a code if you don't floor it when you are supposed to, but I would think you can ignore it.

 

OK. Off to get the vacuum gauge. Will let you know what I find.

Steve

 

Yes on the "T" connection.
Don't worry about the Steering wheel/Brake part of the test(may not apply to your model).
Just watch the gage the first time, skip the WOT test (you will get code 77 and maybe 25).
Then do it a second time with the WOT test.

 

I gotta say ...

Steve, This has been a long challenging and complicated thread ... You have hung right in there like a champ, got a little frustrated/confused for a bit, but recovered awesomely ... I am impressed!

Bill, Vincent, Hats off for sticking it out ... That's Sticktoitiveness!

Kudos to all ...

-Enjoy
fh : )_~

 

Test completed. In the slow KOER mode (using the Actron) the needle barely moved on the gauge and never passed beyond the zero. The Actron called for me to pump the brakes and turn the steering wheel. I did not do that. The Actron asked me to hit the throttle once. I did that but it was lame.

Codes were 41, 34, 73, 74. Going to test again and give a better throttle response.

 

Second test run with a better throttle response. Codes are back to 41 and 34. Still, the vacuum gauge reads 0. It moves in the ) range, but doesn't move out of the range.

 

Photograph your vacuum gage connection.
Slowly increase your Idle from under your hood to 1900 rpm.
Record the vacuum.

 

Did the 1985 have the actuator test ("Output State Check") after the KOEO and Continuous Memory sel-test was done like the mid 90's trucks did?
If they did he could turn all of his actuators on and check to see if the EGR solenoid wire goes to ground.

 

Got a BIG 0! Cannot photograph it. My wife took her iPad and camera. She's a personal chef and takes pics of her food.

So here's the connection: one side of the "T" connects to the hose that typically connects to the EGR valve. One side of the "T" is connected to a small hose the I rigged so as to connect to the EGR. The bottom portion of the "T" is connected to the gauge.

What are your thoughts?

 

That test is done during KOEO, it is one of the first test.